Six people linked to the far right have been detained in connection with a “violent” plot against the French president, Emmanuel Macron, officials said.

The six, who were not identified, were picked up by anti-terrorism units in the eastern French regions of Moselle and Isère and the north-west region of Ille-et-Vilaine, officials added.

A source close to the investigation said the arrests came after reports of a possible plot involving “violent action” aimed at the president. Prosecutors have launched an investigation into a “criminal terrorist association”, a judicial source said.

Another official said: “This investigation is looking into a plot, vague and ill-defined at this stage, involving violent action against the president of the republic.”

In July 2017, a 23-year-old far-right extremist was charged with plotting to assassinate Macron at France’s Bastille Day military parade, which the French leader attended with the US president, Donald Trump.

The man, arrested at home, told investigators he wanted to kill Macron at the 14 July national day parade in Paris, along with “Muslims, Jews, blacks and homosexuals”. Three kitchen knives were found in his car and analysis of his computer found that he had conducted web searches as part of his plot.